This invention relates to fluorinated compositions or compounds, effective to impart water and oil repellency to thermoplastic fibers of polyethylene terephthalate (hereinafter called "PET") or of synthetic long-chain polyamide having recurring polyamide groups as an integral part of the polymer chain (hereinafter called "synthetic linear polyamide" or "nylon"). Such materials function as anti-soil agents.
Polymeric compounds containing fluorinated groups are broadly known for use as anti-soil agents in such articles. In particular, fluorinated polyacrylics, and production thereof, are disclosed in U.S. Pat. Nos. 3,171,861 of Mar. 2, 1965 to Ahlbrecht and 3,514,487 of May 26, 1970 and 3,547,861 of Dec. 15, 1970 both to Anello et al. The fluorinated moiety in the acrylics is derived from a fluorinated alcohol having a perfluoroalkyl group or a fluorinated alkoxy group attached to an alkanol. These polymeric compounds are not in general suitable for application to fibers before use thereof in manufacture of textile fabric, because such additives tend to flake off from a fiber during its processing and conversion to a textile fabric. These polymeric additives should instead be applied to the fabric. Moreover such application should be subsequent to the dyeing of the fabric since such additive may interfere with dyeing.
Furthermore, these polymeric compounds form an immobile coating on the fibers of the fabric. Accordingly, if this coating is disrupted, there is no way that it can restore itself.
It has been proposed to overcome such problems by use of an agent having groups compatible with the fiber-forming polymer and also groups which repel oil and water, thereby providing an amphipathic compound which is compatible with the fiber melt and will migrate to the fiber surface upon exposure to a temperature above the polymer glass transition temperature. In particular, in U.S. Pat. No. 3,646,153 of Feb. 29, 1972 to Oxenrider et al. such compounds are disclosed, including, at col. 3, lines 57-75 and col. 7, lines 47-66, a dicarboxy diamide derived from pyromellitic acid. Such compounds are useful anti-soil agents, but tend to be removed from the fiber on laundering because of the solubility in soap solutions imparted to these compounds by their substituent carboxy groups.
Also of interest in connection with the present invention is U.S. Pat. No. 3,870,748 of Mar. 11, 1975 to Katsushima et al. pertaining to anti-soil agents from acids such as trimellitic and pyromellitic acids esterified by fluorinated alcohols containing hydroxyl substituents in addition to fluorine.